Agate is a micro-crystalline variety of Silica, mainly chalcedony. It characterized by its fine grains and bright colors. Agates are found in various kinds of rocks, but they are classically associated with volcanic rocks and certain metamorphic rocks.

The Greek philosopher and naturalist, Theophrastus discovered the stone along the shore line of Achates river (now called Dirillo in Sicily) sometime between the 4th and 3rd centuries BC.
Agate is most commonly used for hand-stone carving and has been recovered at a number of ancient sites, indicating its widespread use in the ancient world.

Industry uses agates chiefly to make ornaments such as pins, brooches, paper knives, inkstands, marbles and seals. Agate is also still used today for decorative displays, beads, carvings as well as face-polished and tumble-polished specimens of varying size and origin.

Because of its hardness and ability to resist acids, agate is used to make mortars and pestles to crush and mix chemicals. Because of the high polish possible with agate it has been used for leather burnishing tolls for centuries.

Idar-Oberstein was one of the centers which made use of agate on an industrial scale. In the beginning locally found agates were used to make all types of objects for the European market. This became a globalized business around the turn of the 20th century Idar-Oberstein imported large quantities of agate from Brazil.

Making use of a variety of proprietary chemical processes, they produced colored beads that were sold around the globe. Agates have long been used in arts and crafts. The sanctuary of a Presbyterian church in Yachats, Oregon, has six windows with panes made of agates collected from the local beaches.